Aiming at the roof

But for the Marines, the idea is to learn how to overcome the chaos, to think through it, and to perform, regardless of who is shooting at them, or what is in front of them.

This is the Infantry Immersion Trainer, a sophisticated system used at Camp Pendleton, the Marines' major West Coast base, to help prepare Marines for possible combat deployment.

According to an Office of Naval Research Web site, "The Infantry Immersion Trainer (IIT) is a revolutionary training system that prepares Marines and Sailors for deployment to today’s battlefields. The facility uses virtual reality to re-create foreign urban scenes -- right down to the sounds and smells -- to give troops the necessary skills to win and survive in battle overseas."

I've stopped in at Camp Pendleton as part of Road Trip 2012 to see the IIT up close -- even to the point of getting shot covering live training. In this photograph, a Marine aims his weapon at a sniper on the roof of an indoor building that has attacked suddenly.

Laying out muzzles

As the morning begins, instructors at the Infantry Immersion Trainer lay out the gear that Marines will use as they train. The troops will be firing live but will use special bullets topped with soap that are essentially like paintballs. Here, one of the instructors lays out the muzzles that are used to shoot the special bullets.

Magazines and masks

Members of the Marines' 6th Engineer Support Battalion -- a reserve unit -- have come to Camp Pendleton from their bases in Tucson, Ariz., and Bakersfield, Calif., to take part in the Infantry Immersion Trainer.

Although they will be firing special, non-lethal ammunition, they must still wear protective gear, such as the masks on the left. On the right are magazines full of the special ammunition.

Gear line

Marines line up to get their gear for their day at the Infantry Immersion Trainer. They are carrying M-16s without muzzles and will be given a muzzle that has been configured for shooting the special, non-lethal ammunition.

Masking up

Going over plan

An instructor named Darren briefs a group of squad leaders on the layout of an indoor "town" they'll be leading their troops into. Each squad would enter the town on "presence patrol" and would have to suppress an insurgent that fires at them.

Discussing the plan in the dirt

Marine Sgt. Gerry Apple goes over the plan for his squad as they ready to enter an outdoor "town" that is part of the Infantry Immersion Trainer. Marine Capt. Jeremy Masten (foreground) looks on and offers feedback.

IED goes off

The Infantry Immersion Trainer is designed to prepare the Marines not just for dealing with with attackers firing at them with guns. In addition, it features other surprise dangers, including improvised explosive devices.